The present invention relates to an electrophotographic copying machine, and more particularly to an electrophotographic copying machine for copying optional portions of documents on optional portions of copy paper.
Usually copying machines copy the entire portion of an original as it is. However, there arises a need to copy only a portion of the original. In such a case, the portion of the original to be copied is usually cut off for copying, but this procedure is very inconvenient.
To eliminate this inconvenience, various partial copying methods have been proposed. U.S. Pat. No. 4,068,948, for example, discloses a method wherein the unnecessary portion of the original is covered with two movable masking members before copying. In another method of partial copying, the charges on the photosensitive member are erased from the portion thereof corresponding to the unnecessary portion of the original. The charges on the photosensitive member are erased by an illuminating device which comprises an array of lamps arranged between the charger and the developing unit and opposed to the photosensitive member. This method is disclosed, for example, in Unexamined Japanese Patent Publication No. SHO No. 57-41671.
What matters in a partial copying operation is how to specify the portion to be copied. According to Unexamined Japanese Patent Publication No. SHO 57-56859, the portion of the orginal to be copied is surrounded by a marker of a color insensitive to the photosensitive member, and the area marked off is detected by a color sensor for controlling a charge erasing lamp array. However, this method has the objection that the original is colored with the marker. U.S. Pat. No. 4,256,400 discloses a method wherein cursors provided along two edges of a document support glass plate are used for specifying the portion to be copied. This method has the drawback that it is difficult to specify the desired portion since the original is placed on the glass plate face down. Unexamined Japanese Patent Publication No. SHO 58-43480 discloses a method which employs a document feeder (hereinafter referred to as "DF") having a transparent plate ruled into squares on its upper surface and in which the transparent plate is placed over the original to read the coordinates of the portion to be copied using the squares, and the coordinates are entered with numerical keys. The coordinate input system requires the cumbersome procedure of manipulating many keys and involves extreme difficulties in specifying areas other than simple square to rectangular areas.
In conducting partial copying operations, it is desired to locate the partial copying area in a desired position on the copy paper. The above-mentioned Publication No. SHO 58-43480 includes the proposal of shifting the partial copying area on copy paper in the direction of transport thereof by adjusting the copy paper register timing and of shifting the area in a direction perpendicular to the transport direction by causing the DF to feed the original in the perpendicular direction to an adjusted position on the support glass plate. Nevertheless, in view of the relationship between the paper discharge tray of DF and the operation panel of the copying machine, this proposal is in conflict with the development of DF into an auto document feeder (hereinafter referred to as "ADF") for automatically copying a plurality of originals when the ADF is to be realized without making the overall apparatus large-sized.
Further in partial copying, it is cumbersome to select an optimum copy size or magnification for the local copying area. It is also desired to effect such selection automatically.
Another demand as to partial copying is directed to the processing of a plurality of partial copying areas. For example, when an original has two portions which are to be copied separately on two sheets of copy paper or on the front side and rear side of a single sheet of copy paper, the two portions conventionally need to be handled separately. Further for example when a single copy is to be made from two originals each having one portion to be copied, it has been necessary to process the two portions separately.